odd temp sensor behavior

[Lotus7]

Zetec oil temp sensor:

worked fine for a long time, now has odd behavior;
shows sensible data for several laps, then after 20 miles or so the data starts to show random drops to 32 degrees, then spikes back up to 'normal';
frequency of dropouts increases as session time goes by;
but hours later in our next session, data again starts off sensible, then the dropouts start again;
happens every session.

changed the sensor for another new unit, same behavior.
with laptop plugged in and watching 'online' in the paddock, all the wire wiggling we could do wouldn't create the drop.

starting to wonder if this is an AIM issue and not a zetec/sensor issue?
(no one on the AIM forums has yet come up with a definitive idea)

(black is third lap, red is fifth lap, green is 8th lap)

thought welcome. thx

[Steve Davis]

Seems it's likely the line or connector to the AIM. Assuming you are using an EXTENSION from the engine area back to the engine area. Changing the sensor still leaves the same extension line. Get a new extension wire and run it directly between the 2 for a temporary test. If good, replace exension line (or find the problem in it).
Probably...
Steve, FV80

[romoman]

Zetec oil temp sensor:

worked fine for a long time, now has odd behavior;
shows sensible data for several laps, then after 20 miles or so the data starts to show random drops to 32 degrees, then spikes back up to 'normal';
frequency of dropouts increases as session time goes by;
but hours later in our next session, data again starts off sensible, then the dropouts start again;
happens every session.

changed the sensor for another new unit, same behavior.
with laptop plugged in and watching 'online' in the paddock, all the wire wiggling we could do wouldn't create the drop.

starting to wonder if this is an AIM issue and not a zetec/sensor issue?
(no one on the AIM forums has yet come up with a definitive idea)

(black is third lap, red is fifth lap, green is 8th lap)

thought welcome. thx

Which AiM forums? I hadn't seen the question.

Is the sensor to the ECU and then CAN to the dash? If that is the only ECU item falling out, then it's not on the AiM side as the CAN messages are not dropping out.

It sounds heat related, so you would have to do a wiggle test when warm off track. I would also disconnect the sensor while the master power and dash are on to see what the default value is. 32 sounds like a CAN offset and might be the temp you get for an open sensor.

[10rmotor]

Can you change to a different channel?

[helipilot04]

Looks like a grounding problem, when it gets hot your loosing the ground to the sensor in some fashion. Clean the sensor base and or the ground going to the engine. Need a clean, solid ground for digital sensors.